Today, it is generally considered that antidepressants, including Selective 5-HT Reuptake Inhibitors (SSRIs), take 2-4 weeks to reach full clinical effect. In contrast, the side effects occur immediately, and even reduce during this period. Thus, slow onset of action of antidepressants lead to a vulnerable period for patients in which they experience the side effects, but not the therapeutic effects of drugs. There is often a heavy burden on the treating physician to persuade the patient to continue with the treatment during this period. Furthermore, in suicidal patients, as the onset of action is gradual, they may regain initiative without experiencing full reversal symptoms, leading a window of risk for suicide and a frequent requirement for hospitalisation. An antidepressant with fast onset of action would not only be benificial due to the faster symptom reduction, but would also be more acceptable to patients and physicians and reduce the need for and duration of hospitalisation. The same long period to reach full clinical effect has been shown in the treatment of other affective disorders such as anxiety and OCD.